A few small findmnt/mount issues

A few small findmnt/mount issues

[Roger Leigh]

Hi,

Just noticed a few minor deficiencies:

- findmnt does not have column types for DUMP and PASS, so it's
  not possible to get at all the fstab information when using the
  --fstab option, unless there's a way of doing this I'm unaware
  of.  For completeness, it would be very useful to be able to
  retrieve all fstab(5) fields.  This would mean all access to
  mtab and fstab can go via findmnt in our init scripts.

- utab isn't updated on remount for _netdev:
  If I have an fstab entry with _netdev in the fs_mntopts, this
  will get stored in utab when I run "mount /foo".  However, if
  I want to add the option after mount and use
  "mount -o remount,_netdev /foo", this does not cause utab to
  be updated.

  While this might appear contrived, we do actually make use of this
  when filesystems mounted in an initramfs using busybox mount are
  remounted with additional options from fstab with the util-linux
  mount after init starts.  When we had a static mtab, the _netdev
  option would have been added at this point; with utab, we would
  ideally like to be able to update the option via the mount
  interface.  Tested this with 2.20.1, but looking at the source
  looks like it's probably still present unless I misunderstood it.
  May also affect other mount options?

Is there a preferred bugtracker you would like things like this
reporting, or is here OK?


Kind regards,
Roger

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Re: A few small findmnt/mount issues

[Karel Zak]

On Thu, Mar 14, 2013 at 12:21:47AM +0000, Roger Leigh wrote:
> - findmnt does not have column types for DUMP and PASS, so it's
>   not possible to get at all the fstab information when using the
>   --fstab option, unless there's a way of doing this I'm unaware
>   of.  For completeness, it would be very useful to be able to
>   retrieve all fstab(5) fields.  This would mean all access to
>   mtab and fstab can go via findmnt in our init scripts.

 Good idea. Implemented:

$ findmnt --fstab -o TARGET,FREQ,PASSNO
TARGET      FREQ PASSNO
/              1      1
/boot          1      2
/boot/efi      0      0
/home          1      2
/home/kzak     1      2
swap           0      0
/mnt/backup    0      0
/mnt/petra     0      0
/mnt/kzak      0      0

 
> - utab isn't updated on remount for _netdev:
>   If I have an fstab entry with _netdev in the fs_mntopts, this
>   will get stored in utab when I run "mount /foo".  However, if
>   I want to add the option after mount and use
>   "mount -o remount,_netdev /foo", this does not cause utab to
>   be updated.

 Hmm.. works for me (2.22.2 as well as mount(8) from git tree).


  # mount /dev/sdb /mnt/test 
  # cat /run/mount/utab

  # mount -o remount,_netdev /mnt/test

  # cat /run/mount/utab
  SRC=/dev/sdb TARGET=/mnt/test OPTS=_netdev


It would be nice to have reproducible example or/and debug output from
the library:

  LIBMOUNT_DEBUG=0xffff mount -o remount,_netdev ....

>   While this might appear contrived, we do actually make use of this
>   when filesystems mounted in an initramfs using busybox mount are

 BTW, is it really so attractive to use busybox in initramfs? IMHO the
 best way is to consolidate all possible utils and use the same code
 everywhere. (It does not mean that busybox is bad thing, but mix
 utils and environments is often problematic...)

>   interface.  Tested this with 2.20.1, but looking at the source

 Hmm... this is really old release. Update ;-)

>   looks like it's probably still present unless I misunderstood it.
>   May also affect other mount options?
> 
> Is there a preferred bugtracker you would like things like this
> reporting, or is here OK?

 Mailing list is OK.

    Karel

-- 
 Karel Zak  <kzak@redhat.com>
 http://karelzak.blogspot.com